A DL431 24 in 5 way split: fixed configuration I/O A DL251 48 in / 16 out fixed configuration I/O A DL252 16 in / 48 out fixed configuration I/O A DL351 Up to 64 in / 64 out configurable I/O (8 card slots) A DL451 Up to 24 in / 24 out configurable I/O (3 card slots)